Primeval Chamber and similar outposts you get locked out from if you die

Issue: Primeval Chamber and similar outposts you get locked out from if you die

So you enter a Chamber and somehow you die to one of the hard monsters,
then next when you teleport back the entrance is gone and
the outside of the Chamber seems to have "reset"

Whats the reason for this reset?
If its a problem with something else, then cant you just make
a portal to the chamber so you are able to complete it even
if you die once?

Just to mention an example i had a full Primeval Chamber full of stuff and one of the sonic-mobs killed me while i lagged due to the realm not changing after i changed it from Moscow to London. Didnt notice it was still in Moscow in the Mine (but it had changed elsewhere)

Otherwise, thanks for an interesting Delve experience